This invention generally relates to a system for processing construction waste and demolition debris. More particularly, the present invention relates to a mobile system for recovering useful material from construction waste or demolition debris.
In February 1988, the United States Environmental Protection Agency (EPA) created a Municipal Solid Waste Task Force to fashion a strategy for improving the nation""s management of municipal solid waste (MSW). One of the task force""s objectives was to increase the use of source reduction and recycling programs to reduce landfilling of solid waste. In a February 1989 report, the EPA outlined the framework necessary to achieve the task force""s goal of managing 25% of our nation""s MSW through source reduction and recycling and, ultimately, through an integrated solid waste management system. In the early 1990""s, many state legislatures set 1995 as their benchmark year for meeting these recycling and waste management goals. However, as of 1994, only 23 of the 50 states were including construction and demolition (CandD) debris and waste in their recycling rates.
As of 1998, several states have amended their regulations to include both MSW and CandD debris in their new planning guidelines and waste disposal facility reporting. Many states have now incorporated CandD quantities and their associated recovery and recycling into their formal statewide planning reports. In June 1998, the EPA published a long overdue report titled xe2x80x9cCharacterization of Building-Related Construction and Demolition Debris in the Unites States.xe2x80x9d The purpose of this report was to characterize the quantity and the composition of building-related CandD debris and to summarize the waste management practices for this type of waste. The authors of this report estimate that in 1996, an estimated 136 million tons of building-related CandD debris were generated in the United States. Of this amount, 70-80 percent of the CandD debris was disposed in landfills and only 20-30 percent of the debris was recovered for recycling.
It is well known in the recycling industry that the recovered materials markets are the key to the economic survival of recycling programs. If the recovered materials are dirty or contain contaminants and do not meet certain minimum quality standards, the buyers of the materials will lower the prices paid and/or terminate the purchase agreements altogether. To perpetuate the recovered materials markets, then, it is necessary to generate clean, high-quality recovered materials. The current trend in solid waste recovery systems is to incorporate a combination of mechanical devices and manual labor to obtain the clean, high quality material. This approach provides the necessary high-grading (product quality improvement) of the mixed waste materials and allows the materials to be sorted into discreet classifications of constituents (e.g. newspaper, ferrous and aluminum cans, HDPE plastic bottles (milk jugs), PET plastic bottles (soda bottles), etc.).
In the systems that combine mechanical devices with manual labor, the mechanical devices are utilized to create a stream of waste for economy-of-size processing. The manual labor is used for discreet identification and removal of marketable materials from the mixed waste stream. In typical operation, the waste stream is conveyed on a conveyor belt while the manual labor analyzes the material in the waste stream and identifies and removes selected items for further processing, such as recycling or reuse.
Within the United States waste industry, the processing and recovery of CandD waste materials has tended to be a stepchild to the interests of MSW materials. However, as the interest in achieving higher recycling rates and extending the life of existing landfills grows, so does the interest in exploring new options for recovery and recycling of CandD waste.
Several devices currently are being marketed for the processing of CandD waste and debris. These devices tend to be single feedstock processing units, e.g. concrete crushers, wood tub-grinders, rotary or flat bed screens for sizing single-source or mixed materials, and the like. These devices may be stationary as well as portable. In operation, these units are typically transported to the field and combined with other units to form a larger processing system. Typically three to five different large mechanical devices are transported to a field site for CandD operations that may last anywhere from a few weeks to a few years. xe2x80x9cMobilexe2x80x9d units are preferable to xe2x80x9cstationaryxe2x80x9d units due to certain permitting/licensing, marketing, and tax benefits that exist for mobile systems.
In light of the foregoing, there is a need for a self-contained, mobile system for recovering useful material from construction waste or demolition debris.
Accordingly, the present invention is directed to a mobile system for recovering materials from construction waste or demolition debris that preferably obviates one or more of the limitations and disadvantages of prior art construction waste and demolition debris recovery systems. The advantages and purposes of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purposes of the invention will be realized and attained by the elements and combinations particularly pointed out in the appended claims.
To attain the advantages and in accordance with the purposes of the invention, as embodied and broadly described herein, the invention is directed to a mobile system for recovering materials from construction waste or demolition debris. The system includes a mobile wheeled chassis that has at least one picking station. A grapple is mounted on the wheeled chassis for selectively retrieving waste or debris from a jobsite. A screen is disposed on the wheeled chassis and is configured to receive waste or debris from the grapple. The screen sorts the waste or debris into fines and oversized material. There is provided a conveyor that transports the oversized material adjacent to the at least one picking station to allow selected materials to be removed for further processing.
In another aspect, the invention is directed to a mobile system for recovering materials from construction waste or demolition debris. The system includes a mobile wheeled chassis that has at least one picking station. A loading means for selectively retrieving waste or debris from a construction site is disposed on the wheeled chassis.
A sorting means is also disposed on the wheeled chassis and is configured to sort the waste or debris into fines and oversized material. A conveying means is provided for transporting the oversized material adjacent to at least one picking station to allow selected materials to be removed for further processing.
In yet another aspect, the present invention is directed to a method of recovering materials from construction waste or demolition debris. The method includes loading selected construction waste or demolition debris onto a screen disposed on a mobile wheeled chassis. The waste or debris is sorted into fines and oversized material. The oversized material is conveyed adjacent to at least one picking station and selected recoverable materials are removed from the oversized material for further processing.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.